Treating hydrocarbon oils



Jan.-27, 1942. R. F. RUTHRUFF EI'AL' 2,271,097

. TREATING HYDROCARBON OILS "Filed Dec. 29, 1937 INVENTORS ROBRT RUI'HRUFF BY JOSEPH n. ROBERTS [IL/q 1 ATTORNEY Patented Jan. 27, 1942 Robert; F. Bulimia. Nutley, N.. .I.,. and; Joseph. K. Roberts, Flossmoor, Ill., assignors to Standard Oil Company, Chicago, 111., a corporation of Indiana Application December 29 1937- Serial No. 182,193

Claims.

This invention relates to processes for treating I products leaving the viscosity breaking zone are separated into liquid residue and vapors, the vapors being fractionated to separate a heavy condensate oil such as a heavy gas oil and a light reflux condensate such as a light gas oil from a light distillate containing gasoline constituents.

The heavy condensate oil and a portion or all of the liquidresidue separated from theviscosity broken products are passed through a heating zone or coil wherein they are heated to a cracking temperature and maintained under atmospheric pressure or slightly greater. The heated products from the heating zone or coil are then passed or introduced into a coking chamber or drum wherein vapors are separated from residue and heavy constituents are decomposed by the contained heat of the heated products into Vapors and a coke residue which collects in the coking chamber or drum. Vapors, including the vapor products formed. by the coking action in the coking chamber, are passed to a fractionating tower wherein they are fractionated to separate heavy condensate oil such as a heavy gas oil and light reflux. condensate such as a light gas oil from a light distillate containing gasoline constituents. The last mentioned heavy condensate oil is mixed with the charge of relatively heavy oil and passed through the viscosity breaking zone for further cracking treatment.

The relatively light reflux condensate separated from vapors derived from'the viscosity broken products and the light reflux condensate separated from vapors derived from the coking chamber are passed through a cracking zone or coil wherein they are maintained under superatmospheric pressure and at a relatively high temperature to effect the desired extent of cracking. The products from the cracking :zone or coil are passed to an evaporator or separating zoneto separate a liquid residue from vapors. All or a portion of the last mentioned liquid residue is passed to the heating zone orcoil and then to the coking chamber for conversion into vapors and coke residue.

The vapors derived from the products leaving the cracking zone or coil are fractionated to separate a light condensate oil which is preferably recycled through the cracking zone or coil for further cracking treatment from a light distillate product-having the desired" boiling range.

In the drawing there is represented a diagrammatic'illustration showing an apparatus suitable for practicing theprocess of the invention.

Referring now to the drawing, the reference character l0 designates a pump for forcing a relatively heavy charging oil through a line I2 and through a viscosity breaking zone or coil [4 in a heater l6 wherein the heavy charging oil is maintained under superatmospheric pressure and at an elevated temperature to produce a relatively large yield of intermediate constituents suitable forfurther cracking to produce lower boiling hydrocarbons containing gasoline constituents. The products leaving the viscosity breaking zone or coil M are passed through line H! preferably having a pressure reducing valve 20' into an evaporator or separating zone 22 to separate vapors from liquid residue. The liquid residue is Withdrawn from the bottom of the evaporator through line 24' and may be further treated as will be described hereinafter. The vaporspass upwardly through line 26 and are introduced into a fractionating tower 28 wherein they are fractionated to separate heavy condensate oil and light reflux condensate from a light distillate containing gasoline constituents.

The vapors remaining after fractionation in theiractionating tower 28 are passed through line 30 and are cooled and condensed by passing through condenser 32 and the distillate is collected in a receiver 34 having a valved gas outlet 36 and a valved liquid outlet 38; The light reflux condensate is collected on trapout tray 40 having a hood 42 and is withdrawn therefrom and passed through line 44 by pump 46 through a cracking zone or coil 48 in heater 50 as will be later described in more detail.

The heavy condensate oil is withdrawn from the bottom of the fractionating tower 28and is passed through line 52 by pump 54' through a heating coil or zone 56 in heater 58. A portion of the liquidresidue withdrawn from the bottom of the evaporator 22 may be passed through line 59 by pump 60 and combined with the heavy condensate oil passing through line 52 and the combined stream passed through the heating coil or zone 56. In its passage through the heating coil or zone 56 the oil isheated to a cracking temperature and is maintained under atmospheric'pressure or a pressure slightly greater than atmospheric. The oil is passed through the heating zone or coil 56 at a velocity to prevent deposition of coke therein. During its passage through the heating zone or coil 56 the, heavy oil is heated and the heated products are passed through line 6| into a coking chamber or zone 62 maintained at a suitable coking temperature by the contained heat of the heated products. While only one'coking chamber has been shown in the drawingvit is to be understoodlhatf a plurality of such coking chambers is preferably used. The heated products passing through line 6| may be passed through branch lines 64, 66 and 68 into the coking chamber 62.

In the coking chamber 62 the heated products are maintained at a coking temperature by their contained heat to form vapors and a coke residue which collects in the bottom of the coking chamber and which may be removed in any suitable manner through manway I0. The vapors, including the vapor products formed by the coking action in the coking chamber 62, pass upwardly through line 12 into a fractionating tower 14 wherein the vapors are fractionated to separate heavy condensate oil such as a heavy gas oil and light reflux condensate such as a light gas oil from a light distillate containing gasoline constituents. The vapors remaining after fractionation pass overhead through line "I6 and are cooled and condensed by passing through condenser I8, the distillate being collected in a receiver 80 having a valved gas outlet 82 and a valved liquid outlet 84.

The heavy condensate oil from the bottom of the fractionating tower I4 is withdrawn therefrom and passed through line 94 by pump 96 and is then mixed with the heavy charge for passage through the viscosity breaking zone or coil I4.

The light reflux condensate is withdrawn from trapout tray 86 having a hood 88 and is passed through line 90 by pump 02 through the cracking zone or coil 48 before mentioned. The light reflux condensate from trapout tray 86 and the light reflux condensate from trapout tray 40 in fractionating tower 28 are passed through the cracking zone or coil 48 wherein they are maintained under superatmospheric pressure and at a relatively high temperature to effect the desired extent of conversion. The products leave the cracking zone or coil 48 through line. I having a pressure reducing valve I02 and are passed into an evaporator or separating zone I04 to separate Vapors from liquid residue. A quench oil may be introduced through line I05. Theliquid residue is withdrawn from the bottom of the evaporator through line I06 and a portion or all of the liquid residue may be passed through line I08 by pump I I0 and passed through the heating coil or zone 56 and then passed to the coking chamber 62 for conversion into vapors and coke residue.

The vapors separated in the evaporator or separating zone I04 are passed through line II2 to the fractionating tower I I4 to separate light condensate oil from a light distillate having the desired boiling range. The light condensate oil is withdrawn from the bottom of the fractionating tower I I4 and is passed through line I I6 by pump II8 for recycling through the cracking zone or coil 48. The vapors remaining after fractionation in the fractionating tower II4 are passed through line I20 and are cooled and condensed by passing through condenser I22, the distillate being collected in receiver I24 having a valved gas outlet I26 and a valved liquid outlet I28.

A typical operation of one embodiment of the invention will now be given but it is to be understood that the invention is not restricted thereto. A relatively heavy charging oil such as reduced crude oil or other residual oil together with heavy condensate oil from the bottom of the fractionating tower I4 is passed through the viscosity breaking zone or coil I4 wherein the oil is maintained under a pressure of about-75 to 500 pounds per square inch, preferably about 400 pounds per square inch and at a temperature of about 850 to 950 F., preferably about 940 F.

Heavy condensate oil from the bottom of the fractionating tower 28 and all or a portion of the liquid residue from the bottom of the evaporator or separating zone 22 are passed through the heating coil or zone 56 wherein the oil is heated to about 840 to 950 F. and maintained under a pressure from about atmospheric to about 60 pounds per square inch. All or a portion of the residue from the bottom of the evaporator or separating zone I04 is preferably passed through the heating coil or zone 56 together with the heavy condensate oil and liquid residue just described. During passage through the heating coil or zone 56 the oil is heated and the heated products are introduced into the cokin chamber 62 which has been preferably preheated to at least 650 F. and preferably higher. Coking chamber 62 is preferably insulated to prevent heat loss. The coking chamber 62 during the coking operation is maintained under a pressure from atmospheric to about 60 pounds per square inch and at a suitable coking temperature of about 780 to 840 F. by the contained heat of the heated products.

In the coking chamber 62 the heated products are separted into vapors and residue and heavy constituents are decomposed into coke residue and vapors by the contained heat of the heated products. The vapors from coking chamber 62 are fractionated in fractionating tower 14 to separate heavy condensate oil which is directed to the viscosity breaking zone or coil I4 and light iarzfiux condensate which collects on trapout tray The light reflux condensate from trapout tray 86 in fractionating tower I4 and the light reflux condensate from trapout tray 40 in fractionating tower 28 are passed through the cracking zone or coil 48 wherein they are maintained under a pressure of about 200 to 1000 pounds per square inch, preferably about 750 pounds per square inch and at a temperature of about 925 to 1100 F., preferably about 975 F. to effect the desired extent of cracking. The cracked products are passed to the evaporator or separating zone I04 which is maintained under a pressure of about 200 to 300 pounds per square inch to separate vapors from liquid residue. The vapors are fractionated in fractionating tower II 4 to separate light condensate oil which is recycled through the cracking zone or coil 40 from a light distillate having the desired boiling range, which is collected in the receiver I24.

While no means for providing reflux liquid for the top of the fractionating towers or below the trap-out trays therein have been shown in the drawing, it will be understood that reflux liquid is used during the fractionation of the vapors in the fractionating towers according to well known fractionating practice.

While one embodiment of 'the invention has been described it is to be expressly understood that the invention is not restricted thereto and various modifications and adaptations thereof may be made without departing from the spirit of the invention.

We claim:

1. A process for converting higher boiling hydrocarbons into lower boiling hydrocarbons which comprises passing a relatively heavy oil through a viscosity breaking zone wherein it is maintained under superatmospheric pressure and at an elevated temperature to produce a relatively large yield of intermediate constituents suitable for further cracking to produce gasoline constituents, passing the viscosity broken products to a separating zone to separate vapors from liquid residue, fractionating the vapors to separate heavy condensate oil from light reflux condensate, passing heavy condensate oil so obtained and at least a part of the liquid residue separated from the viscosity broken products through a heating zone to raise the temperature thereof to a cracking temperature, passing the heated products to a coking zone wherein the heated products are maintained at a coking temperature by their contained heat to form vapors and coke residue, fractionating the last mentioned vapors to separate heavy condensate oil from a light reflux condensate, directing the last mentioned heavy condensate oil to said viscosity breaking zone, passing the light reflux condensates through a cracking zone wherein they are maintained under superatmospheric pressure and high temperature conditions to efiect the 'desired extent of cracking into lower boiling hydrocarbons including gasoline constituents, separating the products leaving said cracking zone into vapors and liquid residue, fractionating the last mentioned vapors to separate condensate oil from light distillate having the desired boiling range, recycling the condensate oil to said cracking zone, and heating at least a portion of the last mentioned residue to an elevated temperature and directing the heated residue to said coking zone to form vapors and coke residue.

2. A process for converting higher boiling hydrocarbons into lower boiling hydrocarbons which comprises passing a relatively heavy oil through a viscosity breaking zone wherein it is maintained under superatmospheric pressure and at an elevated temperature to produce a relatively large yield of intermediate constituents suitable for further cracking to produce gasoline constituents, passing the viscosity broken products to a separating zone to separate vapors from liquid residue, fractionating the vapors to separate heavy condensate oil from light reflux condensate, passing heavy condensate oil so obtained through a heating zone to raise the temperature thereof to a cracking temperature, passing the heated products to a coking zone wherein the heated products are maintained at a coking temperature by their contained heat to form vapors and coke residue, fractionating the last mentioned vapors to separate heavy condensate oil from a relatively light distillate, directing the last mentioned heavy condensate oil to said viscosity breaking zone, passing the light reflux condensate through a cracking zone wherein it is maintained under superatmospheric pressure and high temperature conditions to effect the desired extent of-cracking thereof into lower boiling hydrocarbons including gasoline constituents, separating the products leaving said cracking zone into vapors and liquid residue, fractionating the last mentioned vapors to separate condensate oil from light distillate having the desired boiling range, recycling the condensate oil to said cracking zone and directing at least a portion of each of said liquid residues to said heating zone.

3. A process for converting higher boiling hydrocarbon oils into lower boiling hydrocarbons which comprises passing a crude residuum stock to a viscosity breaking zone wherein the oil is subjected to cracking temperature under superatmospheric pressure and under viscosity breaking conditions to effect conversion into a relatively large yield of intermediate constituents suitable for further cracking to produce gasoline constituents, passing the viscosity broken products to a separating zone wherein separation of vapors from liquid residue occurs, fractionating the separated vapors to separate heavy reflux condensate from a lighter condensate, passing heavy reflux condensate so obtained to a heating zone wherein the oil is heated at cracking temperature, delivering the resultant heated products to a coking zone wherein the heated products are maintained at a coking temperature by their contained heat and converted into a coke residue, fractionating the evolved vapors from the coking zone to separate heavy reflux condensate from a lighter condensate, combining said lighter condensates and passing the mixture to a cracking zonewherein it is subjected to cracking conditions of temperature and pressure to effect conversion into lower boiling hydrocarbons including gasoline constituents, passing the resultant cracked products into another separating zone wherein separation of vapors from liquid residue takes place, withdrawing said liquid residue, and fractionating the separated vapors to recover a desired distillate.

4. A method as defined in claim 3 wherein said heavy reflux condensate obtained from the vapors evolved in the coking operation is directed into the viscosity breaking zone for conversion therein.

5. A process for converting higher boiling hydrocarbon oils into lower boiling hydrocarbons which comprises passing a crude residuum stock to a viscosity breaking zone wherein the oil is subjected to cracking temperature under superatmospheric pressure and under viscosity breaking conditions toefiect conversion into a relatively large yield of intermediate constituents suitable for further cracking to produce gasoline constituents, .passing the viscosity broken products to a separating zone wherein separation of vapors from liquid residue occurs, fractionating the separated vapors to separate heavy reflux condensate from a lighter condensate, passing heavy reflux condensate so obtained to a heating zone wherein the oil is heated at cracking temperature, delivering the resultant heated products to a coking zone wherein the heated products are maintained at a coking temperature by their contained heat and converted into a coke residue, fractionating the evolved vapors from the coking zone to separate heavy reflux condensate from a lighter condensate, passing the latter reflux condensate to said viscosity breaking zone, combining said lighter condensates and passing the mixture to a cracking zone wherein it is subjected to cracking conditions of temperature and pressure to effect conversion into lower boiling hydrocarbons including gasoline constituents, passing th resultant cracked products into another separating zone wherein separation of vapors from liquid residue takes place, passing resultant separated vapors from the latter separating zone to a separate fractionating zone wherein the vapors are fractionated to separate a distillate product from higher boiling condensate and recycling said higher boiling condensate to said cracking zone for cracking therein together with said lighter condensates.

ROBERT F. RUTHRUFF. JOSEPH K. ROBERTS. 

